"It's around here somewhere."
"I can feel the draft. There must be a big opening."
The circle of light ceased wavering and rested finally on a place at the side of the tunnel, toward the roof. It was just a dark patch, an indentation in the rock, but it was quite large and it seemed to indicate an opening of some kind. It was about five feet from the ground.
"I'll hold the light," Frank said. "See if you can clamber up and investigate that place, Joe."
He stepped back and directed the flashlight so that Joe was able to find a convenient foothold. Joe reached up and secured a grasp on the edge of the natural shelf of rock. Then he managed to scramble up the wall until he swung himself over the ledge. Frank stepped back farther and the light plainly revealed his brother kneeling on the rocky shelf.
"Find anything?" he asked.
"There's a powerful draft of air coming down through here," said Joe, in tones of suppressed excitement. "I think this is a sort of tunnel or air shaft through the rock. I'll turn on my own flashlight."
In a moment Frank could see the glow of his brother's light reflected from the rocks above. Then he heard Joe give a lusty shout of delight.
"It leads on up!" he called. "It is a tunnel running at an angle, and I think it goes to the surface."
"Can you see any light?"